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#26 2006-12-15 13:28:44

noosfractal
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From: Biosphere 1
Registered: 2005-10-04
Posts: 824
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Re: Fishsticks: RIP 2048?

Antarctic sea ice extent is increasing (hmm, don't see that fact often in the press, do you?).

No, I don't.  In fact, you're the very first person I've seen claiming that.

No, well, they don't want to confuse the public with facts.

Do you have a source you can recommend for this information?

Perhaps the The National Snow and Ice Data Center?

http://nsidc.org/seaice/characteristics/difference.html

Even better, plot it yourself ...

http://nsidc.org/data/seaice/visible.html


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#27 2006-12-16 03:56:48

noosfractal
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From: Biosphere 1
Registered: 2005-10-04
Posts: 824
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Re: Fishsticks: RIP 2048?

Krill do not just live at the south pole

My apologies, merely the overwhelming majority live at the south pole.

as these conditions change they struggle

or, in fact, adapt

Krill are one of the lowest and common foods on the food chain.

Agreed!

Cold seas are the most productive seas and as the seas warm they become less productive.

This is, at best, a gross oversimplification, but I think in fact that it is false in general, because I recall recentish articles blaming a particular krill decline on colder water from increased polar melt.  There are 80+ known (so probably 800+ total) species of krill, each with its likes and dislikes.  Modeling the populations of even the most common types is in its infancy.  Mostly, krill populations are limited by food supply - so to model accurately, you would have to model ice-algae and phytoplankton populations, but modeling of these populations is also in its infancy, etc, etc. 

I understand hyping for grant proposals, press releases, etc.  This is fascinating and important science.  I feel privileged to watch it happening.  But we are no where near modeling responses to climate change in this area.


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#28 2006-12-16 07:58:09

Grypd
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From: Scotland, Europe
Registered: 2004-06-07
Posts: 1,879

Re: Fishsticks: RIP 2048?

Krill the wikipedia

Krill

As noted krill are a species that relies on phytoplancton. Which explodes in the aerly summer months in both the north and south feeding on the very nutrient rich seas. They also feed on zooplankton which also relies on cold nutrient rich seas.

Another major problem facing krill is that they are crustaceans so if water has increased CO2 absorbed in it as warmer water does they struggle to form there exoskeletons.

This is, at best, a gross oversimplification, but I think in fact that it is false in general, because I recall recentish articles blaming a particular krill decline on colder water from increased polar melt. There are 80+ known (so probably 800+ total) species of krill, each with its likes and dislikes. Modeling the populations of even the most common types is in its infancy. Mostly, krill populations are limited by food supply - so to model accurately, you would have to model ice-algae and phytoplankton populations, but modeling of these populations is also in its infancy, etc, etc.

I understand hyping for grant proposals, press releases, etc. This is fascinating and important science. I feel privileged to watch it happening. But we are no where near modeling responses to climate change in this area.

It is of course a gross oversimplication but as a general trend it is very true. Phytoplankton has been disturbed before and the Krill has disapeared and we discovered that many other fish stocks disapeared as well. The phytoplankton explodes in the coldest waters and that is why Whales go there to live on the Krill that explodes on the Phytoplankton. There is very little of this in the warmer seas and in some ways these seas are actually for plankton and krill sterile.

When the northern and southern oceans heat up the enviroment that the phytoplankton and Krill desire to swarm will go and so will there capacity to support higher forms of life.

Gross oversimplication, yes but true none the less and it will drastically reduce the seas carrying capacity and our capacity to get fish from the sea.


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#29 2006-12-16 08:28:06

C M Edwards
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From: Lake Charles LA USA
Registered: 2002-04-29
Posts: 1,012

Re: Fishsticks: RIP 2048?

Antarctic sea ice extent is increasing (hmm, don't see that fact often in the press, do you?).

The area covered by antarctic sea ice has shown a small (not statistically significant) increasing trend.
...
The extent of arctic ice in September, when extent is at its annual minimum, is decreasing at a rate of 7.7 percent per decade

Considering the degree of yearly variation in ice cover, it seems they are claiming that the minimum antarctic ice cover is remaining roughly constant while the arctic ice cover is clearly decreasing.  Interesting.  And no, you don't see that in the popular press.

If the rate of antarctic iceberg calving has gone up, then antarctic ice cover should have decreased given a constant rate of formation.  Either the reported rate of iceberg calving is in fact completely normal for the Antarctic, with ice shelf sections the size of Luxembourg heading north every year being just fine, or all of that extra ice is coming from somewhere.


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#30 2006-12-17 04:03:13

noosfractal
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From: Biosphere 1
Registered: 2005-10-04
Posts: 824
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Re: Fishsticks: RIP 2048?

Another major problem facing krill is that they are crustaceans so if water has increased CO2 absorbed in it as warmer water does they struggle to form there exoskeletons.

I assume you're referring to the 2005 Royal Society report ...

Ocean acidification due to increasing atmospheric carbon dioxide
http://www.royalsoc.ac.uk/document.asp?id=3249

which sums up a great deal of research in this area.  Let's have a look at the conclusions of the "Biological impacts" section ...

It is expected that calcifying organisms will find it more difficult to produce and maintain their shells and hard structures. However, the lack of a clear understanding of the mechanisms of calcification and its metabolic or structural function means that it is difficult, at present, to reliably predict the full consequences of CO2-induced ocean acidification on the physiological and ecological fitness of calcifying organisms.

Translation: We don't know.

Gross oversimplication, yes but true none the less and it will drastically reduce the seas carrying capacity and our capacity to get fish from the sea.

Perhaps I'll take a leaf out of C M Edwards book here and ask you what scientific article(s) convinced you this is true?

Wikipedia (since you mentioned it) says that krill biomass is between "13 million and several billion tonnes."  Check out that statement for a moment.  Krill biomass might be 13 million, 130 million or 1.3 billion tonnes.  The only thing this statement communicates is that our knowledge of krill biomass is close to zero.  If we don't know the level of krill biomass, how can we possibly model its response to global warming, or even know whether it is increasing or decreasing in general?


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#31 2006-12-17 04:50:24

noosfractal
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From: Biosphere 1
Registered: 2005-10-04
Posts: 824
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Re: Fishsticks: RIP 2048?

Considering the degree of yearly variation in ice cover, it seems they are claiming that the minimum antarctic ice cover is remaining roughly constant while the arctic ice cover is clearly decreasing.  Interesting.  And no, you don't see that in the popular press.

From the last line on that page ...

Arctic: decrease of 3% per decade (200,000 km2)
Antarctic: increase of 0.8% per decade (100,000 km2)

They label the Arctic figure "significant" and the Antarctic figure "insignificant" but the Antarctic figure is fully 50% of the Arctic in terms of surface area.  That must have taken some pretty careful choice of statistical confidence levels to exclude the Antarctic figure.

Why dismiss the Antarctic increase as "roughly constant"?

To be fair, the Antarctic increase is consistent with global warming.  Global warming means more water vapor in the atmosphere, which means more precipitation, in particular more snow over the Antarctic, so more ice.  For some reason most people seem to miss the fact that a few degrees warming at the poles still leaves them _way_ below the freezing point of water. 

In fact, not a few scenarios have the Antarctic making a _negative_ contribution to sea level because it takes thousands of years for snow that falls at the center of the continent to make its way to the edge.  (I have never seen this discussed in anything remotely approaching the popular press, but check out _Mass Balance of the Cryosphere_, Cambridge University Press, if you are interested).  Most of the projected sea level rise comes from thermal expansion of the ocean rather than ice melt, but our models of thermal transport in the ocean (whether just the surface warms or whether the depths warm too and how much) are so poor that IPCC estimates of sea level change have the now familiar order-of-magnitude uncertainty: 4-40 inches per century.


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#32 2006-12-17 06:02:45

Grypd
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From: Scotland, Europe
Registered: 2004-06-07
Posts: 1,879

Re: Fishsticks: RIP 2048?

Lots of links sorry

Biodiversity and Conservation: A Hypertext Book by Peter J. Bryant

This indicates how the state of global fishing stocks has reduced and even in stocks which are not actively fished but there numbers still drops indicating a loss of biodiversity reduces stocks even in non fished species.

Accelerating Loss of Ocean Species Threatens Human Well-Being

More info on loss of species and decrease in bio diversity this from the National science foundation.

Is the Bering sea warming and affecting the ecosystem: pdf

This is an important piece of goverment research. In the case of Krill the usual blooms of photoplankton did not arrive that year and so the Krill did not develop into there large swarms. It was one of the warmest bering sea years recorded and also the year the salmon did not run no salmon went up the Alaskan rivers to spawn. Other effects was the crab fishing industry that year suffered its worse year ever fishing in the bering sea.

There is a lot more research proving that seas are warming up and we have less captures of fish each year as stocks reduce.

Another point to add is that unlike the artic sea, ice in the antartic is the result of glaciers and we already know that glaciers are like rivers they flow. As the world warms they flow a lot faster and so more ice is flung out to sea. What we also see especially in the Antartic is large ice sheets breaking off from the mainland and the actual ice depth decreasing rapidly.


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